Technical Field
The present disclosure relates to a system for the distribution of radio frequency signals and to a respective implementation method.
Background Art
With reference to radio frequency communication systems, it is known that the so-called passive inter-modulation phenomenon (PIM) occurs in case of the presence of two or more signals in a non-linear device.
The causes of the non-linearity of a device can be numerous, from the presence of oxidized connections to the presence of imperfect contacts.
In any case, the effect of the non-linearity is to generate new additional signals with spurious frequencies which are not only the harmonic frequencies (whole multiples) of the input frequencies, but are also the sum and the difference of the original frequencies and of the multiples of such frequencies.
Some of such inter-modulation distortion products (Inter-modulation Distortion or, in short, IMD) can fall within the reception band of the signals and thus cause a desensitization of the system.
In particular, the inter-modulation products of third order (IMD3) tend to fall within the reception band and are generally the highest in terms of power.
It is therefore necessary to reduce passive inter-modulation to the utmost or at least its effects on the reception branch or branches, in such a way as to make the generated spurious frequencies less invasive.
In particular, the problem of inter-modulation distortion is all the more felt in DAS (Distributed Antenna System) communication systems, wherein different radio operators and different frequency bands combined together are present.